There were some "Silver Slipper" chips that were listed in "The Chip Rack" and the "Official U.S. Guide to Casino Chips" until it was determined that they were from a casino in Canada. The chips were removed from the guides, but sellers on eBay continued to sell them as Las Vegas chips even after they were repeatably informed that they were Canadian. So you may have to wait a while for the sellers of the Joker's Club chips to come clean.